The present invention concerns a centrifugal separator.
Centrifugal separators are well known for removing contaminant particles from the lubricating oil circuit of internal combustion engines and for separating particulate matter from liquids or separating liquids of different densities in a variety of industrial processes. As contaminants accumulate within a centrifuge, it is essential that it is routinely cleaned out in order to maintain effectiveness of operation. For industrial and non-constant use engine applications, it is difficult for a user to know when it is necessary or appropriate to open the centrifuge for cleaning. A centrifuge left too long may result in a sludge compact that is too hard and difficult to remove and a heavy rotor. Conversely, a centrifuge that is opened too early in the service interval may waste valuable service time in checking and may result in use of replaceable components, e.g. paper inserts or liners, prematurely. Therefore, it would be useful to know when the centrifuge is ready to be cleaned without having to stop or open the centrifugal separator assembly.
It is desirable to provide a centrifugal separator which has some means to indicate when the centrifuge is ready to be cleaned without stopping its operation or opening the assembly for visual inspection. It is also desirable to minimise power requirements, avoid requirement for external power source and minimise requirement for replacement of parts.
European patent specification EP 0872282 A discloses a centrifuge rotor provided with an ultrasonic sensor to measure the degree of liquid filling in its interior. This is not practical in most situations.
German patent specification DE10103997 discloses an arrangement for measuring electrical capacitance in a stationary circuit associated with a rotor of centrifugal separator, change in the capacity being indicative of the loading of the rotor with separated particles.
Various rotation sensors have been proposed for centrifugal separators involving, for example, optical sensing means or other signal receiving components mounted in or outside the casing to detect a marker or transmitter on the revolving rotor.